Cassirer's Substance and Function (1910) translates the key theoretical arguments of Leibniz's System and Cohen's philosophy into a modern scientific idiom, weaving the basic themes through a survey of the modern development in logic, mathematics, geometry, physics, chemistry and psychology. Cohen praised the book for its development of the Marburg critique through an immanent discussion of the contemporary sciences, a project that, he noted in a letter to Cassirer, his own work had never accomplished. The central argument of Substance and Function is that the contemporary primacy of the “logic of the mathematical concept of the function […] is not confined to mathematics alone […] but extends over into the field of the knowledge of nature; for the concept of the function constitutes the general schema and model according to which the modern concept of nature has been modeled in its progressive historical development.” The text thus “represents a single problem,” the functionalist definition of part and whole, “which has expanded from a fixed center, drawing ever wider and more concrete fields into its circle” to present a new phenomenology of experience and theory of perception. Substance and Function provides a clear definition of the meaning of function and form in the “system of the sciences” that will then be available as a model for all sciences, and as a means of critique of their limitations, thus completing Cohen's vision of a general critique of science in society.